Fuel delivery systems of the subject character typically include a pump for delivering fuel under pressure from a supply to a fuel consumer, such as an internal combustion engine. A check valve is connected between the pump and the engine for preventing back-flow of fuel from the engine to the pump when the pump is turned off. Fuel pressure is thereby maintained at the engine, resulting in reduced start-up time. Typically, the check valve includes a valve element biased by a spring against a seat within a fuel passage. U.S. Pat. No. 4,697,995 discloses a check valve of the described construction carried by the housing of a fuel pump, and thus constructed as a unitary assembly with the pump. The valve element is "free floating" in the passage, and the spring is tapered toward the valve element to help stabilize the element against lateral motion.
Although fuel delivery systems of the described character, as illustrated in the noted U.S. Patent, have enjoyed substantial commercial acceptance and success, improvements remain desirable. For example, positive displacement fuel pumps conventionally employed in automotive engine fuel delivery systems typically are of construction that deliver intermittent fuel pressure pulses over and above a constant or average fuel pressure. These pressure pulsations affect engine operation and can present a noise problem, and reduction or elimination thereof is desirable. Further, there is a marked tendency for the valve element to oscillate laterally around an average position, thus exacerbating the problem of pressure pulses in the pump output.
A general object of the present invention, therefore, is to provide a check valve that finds particular utility in fuel delivery systems of the subject character, but also enjoys wide application in other flow control environments of similar nature, and that helps reduce or eliminate pressure pulses in the fuel delivery line. A more specific object of the invention is to provide a check valve of the described character in which lateral motion of the valve element is restrained, while axial motion is free but damped.